Ants reside in, among other places, nests located in underground cavities they have excavated in the soil, in rotting wood, or in other locations which provide an ideal environment for microorganisms such as bacteria and fungi to thrive. Although both bacteria and fungi are potential serious health hazards for ants, ant colonies are rarely afflicted by bacterial or fungal infections. This remarkable immunity to such infections can be attributed to the secretions from the metapleural gland, which is located in the thorax of adult ants.
The substances secreted by the metapleural gland of ants provide a mixture of chemicals which is highly effective in killing or preventing the growth of microorganisms such as bacteria and fungi. The metapleural gland is a paired structure at the posterolateral end of the alitrunk, and is found only in ants (see, Holldobler and Engel-Siegel, 1984). The gland has been thought to be involved in the antibiotic defense against microorganisms of many ant species (see, Maschwitz et al., 1970; Maschwitz, 1974). Study of the antibiotic properties of the metapleural gland secretion has identified a number of active chemical compounds and their functions.
It has been suggested that metathoracic (metapleural) gland secretions are involved in the control of foreign bacteria and fungi and possibly viruses in the fungus gardens of Atta sexdens rubropilosa, a leaf-cutting ant of Central and South America (see, Attygalle and Morgan, “Chemicals from the Glands of Ants,” 1983). The compounds identified in secretions from the metathoracic gland of Atta sexdens rubropilosa are primarily carboxylic acids, and include the following: phenylacetic acid (PAA), 3-indoleacetic acid (IAA), 3-hydroxydecanoic acid (myrmicacin), 3-hydroxyoctanoic acid and 3-hydroxyhexanoic acid. PAA and 3-indoleacetic acid have plant growth regulatory activities. Myrmicacin and the two related hydroxy-acids are believed to be used by Atta sexdens rubropilosa to prevent germination of undesirable fungal spores. Myrmicacin is known to possess a number of other biocidal properties, including pollen germination-inhibitory activity, animal cell growth-inhibiting activity, and antimicrobial activity (see, T. Iwadara et al., Yakugaku, 1979, 28, 309).
In contrast to the carboxylic acid-containing secretion from A. sexdens, the metapleural gland chemical secretion from the Australian ant Crematogaster deformis consists primarily of phenols (see, Attygalle et al., “Chemical Composition and Function of Metapleural Gland Secretion of the Ant Crematogaster deformis, Smith (see, Hymenoptera: Myrmicinae)”, Journal of Chemical Ecology, Vol. 15, No. 1, 1989). These phenols include: 3-propylphenol, 3-pentylphenol, mellein, 5-propylresorcinol and 5-pentylresorcinol. The secretion from the metapleural gland of Crematogaster deformis is also known to have antibacterial and antifungal properties.
Antibacterial and antifungal agents are important for the treatment of many medical conditions. In particular, the treatment of dermatological conditions frequently involves the use of a topical antifungal agent on skin, mucous membranes and hair lesions. Moreover, the danger of hospital-acquired infection has intensified with the rise of new strains of common microbes that are resistant to antibiotics. According to the Centers for Disease Control and Prevention, 5 percent of the people admitted to American hospitals, about 1.8 million patients a year, will pick up an infection there (see, Yoffe, “Unclean Hands, Hospital Dangers,” The New York Times, Nov. 15, 1999, page 9). Twenty thousand of them will die as a direct result of contracting an infection in the hospital; by contrast, 17,171 Americans died of AIDS in 1998. The infections will cost $4.5 billion to treat, the CDC estimates, and it says better infection control could have prevented one-third of those cases.
Clearly, there currently exists a need for more efficacious antimicrobial agents to treat medical conditions in humans and animals. The present invention, effective against such a surprisingly wide spectrum of organisms, satisfies such a need.